Method for signal processing and an apparatus therefore

ABSTRACT

An apparatus for signal processing, wherein a disc is placed on a turntable and is provided with a groove which can be followed by the pick-up element, and employing a time-code signal wherein during use of the disc the said time-code signal controls the digital audio source.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 11/355,851, entitled “Disc For Use In An ApparatusFor Signal Processing, And Such An Apparatus”, filed on Feb. 15, 2006which is a divisional application of patent application Ser. No.10/133,846, entitled “Disc For Use In An Apparatus For SignalProcessing, And Such An Apparatus”, filed on Apr. 26, 2002, which is aContinuation of International Application Number PCT/NL01/00055 filed onJan. 26, 2001 entitled “Disc For Use In An Apparatus For SignalProcessing, And Such An Apparatus”, which is a continuation and claimspriority to The Netherlands application number NL 1014526, entitled“Disc For Use In An Apparatus For Signal Processing, And Such AnApparatus”, filed Feb. 29, 2000. The specification and claims thereofare incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

INTRODUCTION

The invention primarily relates to a disc for use in an apparatus forsignal processing. Further, the invention relates to such an apparatusfor signal processing.

BACKGROUND OF THE INVENTION

From WO 97/01168, a system is known for the digital processing of audiosignals which is particularly suitable for disc jockeys and scratchartists. The speed and direction of a digital audio signal, for instancederived from a CD player, can be controlled according to this citationby the manual control of a rotational element. This rotational elementis placed for instance on a turntable of a conventional record playerand is being read by means of an optical sensor determining the speedand direction of rotation of the turntable. The data that are obtainedthereby are being used to control the speed and direction ofreproduction of the CD player. The problem associated with this knownapparatus is, however, that it is hardly usable by disc jockeys and inscratch applications for the reason that from a given position of thereading head of the CD player only continuously developing relativemovements are possible that depend on the control of the earliermentioned rotational element. In the known apparatus, it is for instancenot possible to make swift reproductions of different musical segmentson the CD in a way that is reproducible and can be controlledsatisfactorily. Also the authentic scratch sound which can be realizedby means of a conventional record, cannot be obtained with the knownapparatus.

SUMMARY OF THE INVENTION

With the invention it is intended to improve this and to provide asystem which allows to provide a sound impression with a digital soundsource which conforms to the possibilities that exist with conventionalrecords, and with which quickly digitally recorded (musical) fragmentscan be located.

In a first aspect of the invention, a disc is proposed therefore whichis designed for use in such an apparatus for signal processing, suchthat the disc during its use is placed on the turntable and is providedwith a groove which can be followed by the pick-up element, and whichcomprises a time-code signal wherein during use of the disc the saidtime-code signal controls the digital audio source.

A practical embodiment of the disc is characterized in that thetime-code signal is an absolute time-code signal that is comprised inthe groove in a predetermined number subsequently arranged discretesteps. It is advisable to select the number of discrete steps in suchway that the resolution is sufficiently high to realize the intendedeffect. In practice this means that the number of discrete steps maycount five per second.

From a view point of cost efficiency and also to make a naturalconnection to the known scratching techniques with conventional records,it is desirable that the time-code signal is modulated on a carrierfrequency in the audible range between 20 and 20,000 Hz. In this way, itis possible to simply use normal audio equipment for playing the disc.

In a further aspect of the invention, the apparatus for signalprocessing is so equipped that the pick-up element feeds a digitalfilter which has a phase-locked loop circuit for detecting and followinga carrier frequency, and a demodulation circuit for demodulating thetime-code signal that is modulated on the carrier frequency. The discand the apparatus for signal processing can then cooperate such that theabsolute time-code signal that is present on the disc, provides thecontrol for the digital audio source.

It is further advantageous that the groove of the disc comprises atime-code signal in both the left and the right channel, which aremutually shifted in phase. In this way, a quick determination of thedirection in respect of the rotation of the disc can be extracted.

Appropriately then the apparatus is equipped with a detection device fordetermining a phase difference between the time-code signal demodulatedfrom the left and the right signal, respectively. In this way, thedesired direction of play of the digital audio equipment can bedetermined already when the needle is lowered onto the disc according tothe invention without noticeable delay, enhancing the impression thatone is working with an entirely conventional analogue audioinstallation.

A suitable embodiment of the apparatus is characterized in that itcomprises a digital audio buffer being under control of the time-codesignal, and that the digital audio buffer is connected to a digitaloutput filter which feeds a signal output which is selected from thegroup formed by a digital electric output socket, a digital optic signaloutput, and a D/A converter.

The scratch effect can be manufactured in such an apparatus particularlyadequately when it comprises control logic being fed by the time-codesignal for determining a velocity signal being a measure for the speedof change of the time-code signal, and that the digital output filter isbeing controlled by the said control logic.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further elucidated in respect of anon-limiting embodiment explaining the disc and its use in an apparatusaccording to the invention in a schematic diagram.

FIG. 1 shows schematically the apparatus for signal processing accordingto according to one embodiment of the present invention and the disc tobe used thereby.

FIG. 2 show as block diagrams the signal processing applied in theapparatus according to one embodiment of the present invention.

FIG. 3 then show as block diagrams the signal processing applied in theapparatus according to according to one embodiment of the presentinvention the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a disc 1.1 which is manufactured according to knownmanufacturing techniques that have been in use for many years now in themanufacture of conventional records. The disc 1.1 is provided with anabsolute time-code signal by making use of a time-code generator 1.2controlling a modulator 1.3 which supplies a carrier frequency modulatedby the time-code generator 1.2 and which is applied to the disc 1.1 asthe only signal. Block 1.4 shows the conventional manufacturing methodof recording, making of the master disc, and pressing the final vinyldisc 1.1. The disc 1.1 can be placed on a turntable 1.5 of a recordplayer 1.6, which is further provided with an arm 1.7 and a pick-upelement 1.8.

The pick-up element 1.8 can follow the groove in the disc 1.1 thatcomprises the absolute time-code signal, and the pick-up element 1.8 isconnected to the apparatus part 1.9 for demodulating the carrier signalin order to provide the (digital) time-code signal, which serves for thecontrol of the digital audio source 1.10, for instance a CD player, aDVD player, an MP3 reproduction device, or the like.

The operation of the apparatus part 1.9 according to FIG. 1 willhereafter be further elucidated with reference to FIG. 2. The operationof the digital audio source 1.10 which stands under control of thetime-code signal will hereafter be further elucidated with reference toFIG. 3.

Referring now first to FIG. 2, it is shown that the signal that isderived from the pick-up element 1.8 according to FIG. 1, is fed to ainput buffer 2.1 from which a signal may be finally led to a mixingtable 2.2 in order to provide for the situation that the turntable 1.5according to FIG. 1 carries a conventional analogue vinyl record. Thejust-mentioned input buffer 2.1 feeds a preamplifier 2.3, provided witha low rejector circuit, and which feeds in turn an analogue/digitalconverter 2.4, for instance a 16-bit or 20-bit converter, depending onthe desired resolution. The reference numerals 2.5, 2.6 and 2.7 refer toa digital filter, the operation of which depends on, inter alia, thespeed of movement of the disc 1.1 according to FIG. 1 vis-a-vis thepick-up element 1.8. The apparatus part 2.7 of FIG. 2 may comprise aphase-locked loop circuit for detecting and following the carrierfrequency which is provided on the disc 1.1 according to FIG. 1. In thecurrent implementation, however, use is made of a moving average filtersupplemented with detection means for detecting a stand-still of thedisc 1.1. Furthermore, demodulation takes place in the circuit ofapparatus part 2.6 for demodulating the time-code signal that ismodulated on the carrier frequency. Although the above subject matter isshown and explained as the signal in a single channel, it is preferableaccording to the invention that a left and a right channel is present,and that the detection apparatus which forms part of the digital filter2.5, 2.6, 2.7 is made in duplicate so as to allow a phase differencebetween the left and the right channel carrying the demodulatedtime-code signal to be determined. In this manner, the correct place anddirection of movement of the disc 1.1 in relation to the pick-up element1.8 according to FIG. 1 can be determined with high resolution.

The phase difference between the left and right channel is useful toextract the directional information very quickly when the pick-upelement 1.8 is suddenly lowered onto the rotating disc 1.1. The absolutetime-code which is determined from the carrier frequency is subsequentlyused together with the relative time-code, which is based on thedifference between the left and the right channel, to determine anaccurate time-code signal 2.10 which serves to control the digital audiosource 1.10 as shown in FIG. 1. The time-code signal 2.10 of FIG. 2 istherefore read into apparatus part 3.1 (see FIG. 3) of the digital audiosource, wherein same provides a direct control of a digital audio reader3.2 reading the desired digital information from the correct place offor instance a CD disc. This digital audio information is beingtransferred from apparatus part 3.2 to a digital output filter 3.5 whichis being controlled by control logic 3.4, and which determines from thetime-code signal which is read into apparatus part 3.1, the speed ofchange of the time-code signal. This speed of change signal which isderived from the time-code signal, determines the parameters of thedigital output filter 3.5. In a manner known to the expert, the digitaloutput filter 3.5 can then feed a digital electric output socket, adigital optical signal output, or a D/A converter. This last provisionis shown in the Figure with reference numeral 3.6.

The present invention has been described in terms of preferredembodiments, however, it will be appreciated that various modificationsand improvements may be made to the described embodiments withoutdeparting from the scope of the invention.

1. A method for controlling a digital audio source, comprising: playinga disc on a turntable, wherein the disc comprises control signal;following a groove in the disc with a pick-up element, wherein thecontrol signal is derived from the disc by the pick-up element;modulating the control signal on a carrier frequency in the audiblerange between 20 and 20,000 Hz; demodulating the control signal; andreading the demodulated control signal into a receiver to providecontrol of a digital audio source.
 2. The method according to claim 1,wherein the control signal comprises a time-code signal.
 3. The methodaccording to claim 2, wherein the disc comprises only time-code signals.4. The method according to claim 1, including applying an absolutetime-code control signal on the disc.
 5. The method according to claim1, wherein control of the digital audio source includes controlling thespeed of the play of the digital audio source.
 6. The method accordingto claim 1, wherein control of the digital audio source includescontrolling the direction of the play of the digital audio source. 7.The method according to claim 6, including detecting a phase differencebetween the control signal demodulated from a right channel and a leftchannel for determining the direction of play for the digital audiosource.
 8. The method according to claim 1, including producing ascratch effect by the digital audio source.
 9. The method according toclaim 1, wherein the digital audio source plays music while under thecontrol of the demodulated control signal.
 10. The method according toclaim 1, wherein the control signal is modulated on a single channel.11. The method according to claim 1, wherein digitally recordedfragments can be located for play on the digital audio source with thedemodulated control signal.
 12. The method according to claim 1, whereinthe digital audio source comprises a CD player, a DVD player, and an MP3device.
 13. The method according to claim 1, further comprising:deriving a signal from the disc by the pick-up element, wherein the discis a conventional analogue vinyl record; feeding the derived signal intoa mixing table; feeding the modulated control signal into a digitalfilter; and using the output of the digital filter to control thedigital audio source.
 14. A method of using a time-code signal tocontrol a digital audio source, comprising: playing a disc on aturntable, wherein the disc includes time-code signals; deriving atime-code signal from the disc while the disc is being played on theturntable; modulating the derived time-code signal on a carrierfrequency in the audible range between 20 and 20,000 Hz; feeding themodulated time-code signal into a digital filter; demodulating thetime-code signal; and reading the demodulated time-code signal into areceiver to provide control of a digital audio source.
 15. An apparatusfor controlling a digital audio source, comprising: a turntable; a disccomprising a time-code signal, wherein the disc is placed on theturntable; a pick-up element deriving a time-code signal from the discon the turntable; a carrier frequency in the audible range of 20 to20,000 Hz for modulating the time-code signal from the pick-up element;a filter for demodulating the time-code signal; and a time-code receiverfor receiving the demodulated time-code signal to be used to control adigital audio source.
 16. The apparatus according to claim 15, includinga digital audio source controlled by the demodulated time-code signal.17. The apparatus according to claim 16, wherein the digital audiosource comprises a CD player, a DVD player, and an MP3 device.
 18. Theapparatus according to claim 15, wherein the speed of the play of adigital audio source is controlled by the apparatus.
 19. The apparatusaccording to claim 15, wherein the direction of the play of a digitalaudio source is controlled by the apparatus.
 20. The apparatus accordingto claim 15, wherein the modulated time-code signal comprises a rightchannel and a left channel.
 21. The apparatus according to claim 20,wherein the direction of the play of a digital audio source iscontrolled by detecting a phase difference between the right channel andthe left channel.